The fact sheets on the Health Effects Notebook for Hazardous Air Pollutants describe the effects on human health of substances that are defined as hazardous by the 1990 amendments of the Clean Air Act: http://www.epa.gov/ttnatw01/hlthef/hapindex.html

ACToR is one of many EPA tools available for those interested in chemical toxicity to find data about potential chemical risks to human health and the environment. The data warehouse:

Is a collection of databases collated or developed by the US EPA Computational Toxicology Research Program.

Aggregates data from over 500 public sources on over 500,000 environmental chemicals searchable by chemical name, other identifiers, and by chemical structure.

Data includes chemical structure, physico-chemical values, in vitro assay data and in vivo toxicology data. Chemicals include, but are not limited to, high and medium production volume industrial chemicals, pesticides (active and inert ingredients), and potential ground and drinking water contaminants.

Provides a connection to another EPA chemical screening tool called ToxCast: http://epa.gov/ncct/toxcast/, a multi-year, multi-million dollar effort that uses advanced science tools to help efficiently understand biological processes impacted by chemicals that may lead to adverse health effects.

If you have additional questions regarding drinking water contaminants, you can contact the Safe Drinking Water Hotline at 1-800-426-4791 or ask a question using the Frequently Asked Questions database: http://safewater.supportportal.com/

Here are some additional non-EPA resources which can provide assistance:

"The ATSDR ToxFAQs is a series of summaries about hazardous substances developed by the ATSDR Division of Toxicology. Information for this series is excerpted from the ATSDR Toxicological Profiles and Public Health Statements. Each fact sheet serves as a quick and easy to understand guide. Answers are provided to the most frequently asked questions (FAQs) about exposure to hazardous substances found around hazardous waste sites and the effects of exposure on human health." http://www.atsdr.cdc.gov/toxfaqs/index.asp#bookmark01

“Haz-Map is an occupational health database designed for health and safety professionals and for consumers seeking information about the health effects of exposure to chemicals and biological agents:”http://www.nlm.nih.gov/pubs/factsheets/hazmap.html

"An ICSC summarizes essential health and safety information on chemicals for their use at the "shop floor" level by workers and employers in factories, agriculture, construction and other work places."

You may also be interested in browsing the resources in these Frequently Asked Questions: